Gardenia (Gardenia jasminoides) has been a favorite landscape plant in the warmer areas of the United States for more than a century. Popularity of the species has been encouraged, in large part, by the attractiveness of the plants and the allure of the pleasantly aromatic flowers. Additionally, the species is quite adaptable to various cultural methods and has modest to long-term life expectancy. There is a consistent lack of seed production in most cultivars despite frequent production of pollen and pistillate structures which leads to the presumption that most present-day cultivars have originated as asexual deviants. The species has few important cultural problems other than nematode infestation for which no cultivars of G. jasminoides are known to exhibit tolerance. Thus, a sizeable share of the plants produced for retail sale are now grafted onto stocks of G. thunbergia, the only recognized nematode-resistant species of the genus, and the price to consumer must reflect this additional production cost. Unfortunately, this rootstock species is intolerant of freezing temperatures which thereby limits outdoor culture of grafted plants to zone 8 or warmer.
All plants for the project herein described were grown in the open at the address given above. Ambient air temperature during the duration of this period ranged from approximately 4-22 C in winter to 22-34 C in summer with occasional, sometimes consecutive, nights of −5 C from January-March. Supplemental irrigation as needed was obtained from the local water service. Early in this study the water tested approximately ph 7+ but was later changed to about ph 6.5. Test plants for nematode screening were grown in new plastic pots in a modification of the local ‘Traxler Mix’ that included only soil and sand with no more than 5% (by volume) ‘pearlite’ and no pine bark or peat. All pots were placed on new, black plastic ground cover and given quarterly 8-8-8 fertilizer with minor elements by hand.
The discovery of a reliable seed-producing cultivar of G. jasminoides, i.e. ‘Star Bright’ made possible horticultural improvement through controlled breeding. In 2003, a pollination on ‘Star Bright’ was made with pollen from G. thunbergia and the resulting seedlings all were first exposed to Southern root-knot nematode (Meloidogyne incognita, race 2) in 2004. Inoculum for each of these inoculations was prepared by laboratory staff of the Nematology Department, University of Florida, Gainesville, Fla. Three years later the plant herein described was found to have the basic horticultural features of desirable cultivars as well as demonstrated resistance to nematode infestation.